Adult giant swallowtails are the largest butterfly in Missouri. The overall color of wings (top side) and body is dark blackish-brown, with bands composed of several yellow spots. There is a yellow spot at the tip of each hindwing “tail.” The undersides of wings are primarily yellow, with black, blue and red markings. There are yellow stripes on the abdomen.
Larvae vary depending on stage of development. Overall the coloring is brown with grayish-white markings, a patch at the end of the abdomen, and a wide saddle mark of the same color in center of the body. The osmetria (hornlike appendages that protrude when the larva is disturbed) are pinkish or red.